Spinning tires/VLSD question

[s14kaibigan]

Ok, I was doing burnouts the other day with my tires in a little standing puddle of water. My rear end kicked to the right a little and then stayed there while I was burning out. A friend who was watching said that my right tire was on dry asphalt and it stopped spinning while the other one was still going. By the way, I burned out by popping the clutch and then pressing on the brakes while I held throttle. Anyways, my question is why would one tire stop spinning if I have VLSD? Is it because one tire was in the water while the other was on pavement? Maybe my brakes caught the wheel what was on the pavement because it stopped spinning as fast as the other one? Since then I haven't burned out because I don't understand why that happened. My car seems to be running perfectly fine. So, well, thanks ahead of time for the help.

[240_Keyy]

I have done almost that exact same thing, but both of my tires spin...

[trpower7]

With a VLSD both tires should spin no matter what. perhaps the viscous coupling is shot to s*** and it's acting like an open. Go do a burnout on normal pavement and look for two streaks. Put it on jacks and do the one wheel spin thing, etc.

[MadSideways]

With a VLSD both tires should spin no matter what.

This is not true, that would only occur if it was a welded diff or 2-way diff. An open puck differential sends power to the wheel with the least resistance. An LSD sends power to the wheel with the most resistance.

When sitting on regular pavement, both tires have the same resistance so they get the same amount of power, hence the two-wheel burnout.

However, when putting one wheel in a puddle, and the other's on pavement, the pavement wheel will take precidence and get the most horse power, causeing the car to have uneven traction. And an open-puck differential would spin one tire, because its not resisting, taking presidence with the tire in the puddle.

On a side note, the r200v VLSD is not a 2 way LSD, so at times it will revert to an open puck differential...(under braking, non-accelleration, deceleration, not enough brake-away torque - 50lbs)...

My guess is, your vLSD was running as an open-puck diff because there was not enough break away torque, and then heated up forcing the vLSD to briefly engage, and the tire on the pavement caught and made the car slide out....

[C-Kwik]

VSLD's tend to be a bit on the weak side. At least the one's I've worked with. Too much difference in traction will cause the effect you experienced. VLSDs are nothing more than an open diff with a viscous coupling in the center. It increases resistance to allowing the output shafts from turning in opposite directions.

Madsideways: a VLSD is not torque sensing. And it does not lock. Add opposite torque to both shafts and it will spin at a rate somewhat linearly with the amount of torque. In other words, apply more torque and it will spin faster. But it will always provide resistance. So there is no real break-away torque with a VLSD. And it reacts the same in both directions so it is in a sense a 2-way. Conversely, the greater the difference in opposing shaft speeds, the more resistance it applies. But other than the effects of heat, the increase is linear.

Break-away torque is more applicable to clutch type LSD's where the clutch remains fully locked up to a certain torque difference, then it allows some slip. The term can be used on a helical LSD as well, but helicals react to torque and increase the locking force with more torque so it is harder to measure.

[NEED4BOOST]

so far from what I have read here, rear end does the same thing. I can put one wheel in grass and the or on pavement and the one with the least resistance will spin (either side).

Now my question is how is this in anyway beneficial for traction purposes? Or handling? I mean if a VLSD is more like a glorified open-puck diff then what benefit does it serve on a track? It doesn't sound like much, because when you load the outside tire during cornering, the inside tire will spin (least resistance) and therefore limiting your handling capabilities. Unless the VLSD is actually working and me not know it. The car handles very well (expert level driver) but I'm new that well educated in lsd's....enlighten me.

I have heard and have been told that there is certain fluids that should be used for our rear ends (I was told after the fact of getting mine changed). I am currently running mobil 1 sythetic gear oil, I don't know if that is fine or not. I was told to be using a silicone fluid or something like that.

Feedback is definitely appreciated!

-Seth

[C-Kwik]

Because it still transfers more torque to the tire with less traction then an open diff. There is a huge difference in traction when you have two different road surfaces involved. The VLSD from Nissan was not really intended for off-pavement or even half-off pavement driving.

As far any special oil, it is not needed. The coupling is sealed and is not servicable. But there should not be a need to. Any decent gear oil will do just fine.

[Exar-Kun]

I just wanted to note something, that what you did was dumb. Popping the clutch then holding the brake to do a burnout is NOT a good idea, it puts massive strain on your transmision(internals, mounts, etc) and brakes, tires and chassis. Its not a good idea. Otherwise, C-kwick is right on target.-chet

[NEED4BOOST]

My question still stands...is a VLSD beneficial at all for road courses or is it no different than running an open diff?

[C-Kwik]

Yes, it is. You can put more power down exiting corners or in other words, you can ease onto the gas a little sooner.

[trpower7]

All this is true, I guess I'm used to working with two way differentials. And yes, the braking while doing a burnout is INCREDIBLY dumb, doing stuff like that is likely to blow up a driveline regardless. Redline gear oil is definetly favorable for your application, a good 80W-90 will work great. VLSD is beneficial in all applications, drive on an open and watch how easy you can make just one spin.

[Kaioshin1982]

just a stupid question, since popping the clutch and then breaking to do a burnout is extremely bad, is there another way to do it? or just dont do burnouts..

[TomsMR2]

^^ um.. pop the clutch and press the gas. its not a science.

[C-Kwik]

All this is true, I guess I'm used to working with two way differentials. And yes, the braking while doing a burnout is INCREDIBLY dumb, doing stuff like that is likely to blow up a driveline regardless. Redline gear oil is definetly favorable for your application, a good 80W-90 will work great. VLSD is beneficial in all applications, drive on an open and watch how easy you can make just one spin.

Honestly, you guys are exaggerating this quite a bit. It would be dumb to hold down your rear brakes as hard as you can while doing a burn out. But it does not take a lot of braking force to hold a car in place during a standing burnout. If you ease into a burnout and get on the brake just enough, I see no reason why your drivetrain would give. Unless you have a lot of power and a clutch that won't slip until you reach levels of torque that are beyond the drivetrain's ability to handle them. Better yet, go back to on of SCC's USCC competition. Look at the dual motor Tiburon. If he can do a burnout where the motors are turtning opposing directions, there is no reason we can't do a standing burnout with a light brake application.

[Exar-Kun]

except for the wear and tear it still places on componenets of the drivetrain, regardless of how well the tires are spinning... exageration maybe, but you're still placing a good bit of strain on the car, especially if the tire is sticky enough and/or the car doesnt have enough power to spin the tires freely.Just pop the clutch and do it that wy, if you cant, you weren't meant to do it anyways, get more horespower and torque, then try again.-chet

[float_6969]

NEED4BOOST-if you are having problems with the VLSD working like an open diff and you recently changed the oil, I think that is where your problem is from. Everytime that I've changed the oil in a VLSD, I've put an LSD addative in and I've never had a problem with it not working right. Go to your local auto parts store and ask for positrac/lsd addative and they should know what your talking about. It's ususally over w/the gear oils. I've never had any complaints about how my VLSD works. I can do a standing burnout and both tires will always spin. I've also done simultanious lowtraction/hightraction acceleration and my VLSD has always held on just fine. (put one wheel on gravel, the other on pavement) If you are having problems with the operation of you VLSD, I would reccomend changing the fluid and adding the LSD addative.

[C-Kwik]

This has been said many, many times before. The VLSD does not require any special fluids. The viscous coupling itself is sealed with it's own silicone fluid inside. It is not servicible. The fluid you put into the carrier only lubricates the gears inside, just like in an open diff.

[Exar-Kun]

:withstup

[NEED4BOOST]

This has been said many, many times before. The VLSD does not require any special fluids. The viscous coupling itself is sealed with it's own silicone fluid inside. It is not servicible. The fluid you put into the carrier only lubricates the gears inside, just like in an open diff.

But it wouldn't hurt for me to try though. I think I may actually give up on my rear end after I try the fluid and just buy a Nizmo pumkin

[C-Kwik]

You can do anything you want. But I'm just saying it won't do you any good. But hey, it's your money...